With the development of touch screen technology, each company introduces different touch techniques. Based on principles, the touch techniques mainly have following types: resistive touch screens, capacitive touch screens, infrared touch screens, surface acoustic wave touch screens, electromagnetic touch screens, dispersive signal touch screens, frustrated total internal reflection touch screens, and the like. Based on structure, the touch techniques are divided into following types: out-cell touch screens (double-layer), screens with touch sensor in coverage surface (single-layer), screens with touch sensor on panels (on-cell), screens with touch sensor inside panels (in-cell), and the like.
With technology development, thinner whole modules is a developing trend of touch panels, thus the touch structure develops from out-cell touch sensor to in-cell touch sensor, which may not only achieve the thinner touch panels, but also greatly reduce cost of touch screens.
Recently, touch sensor arranged inside panels (in-cell) are mainly divided into three kinds of techniques: resistive technique, capacitive technique and optical technique. The resistive technique belongs to a low side sensing technique, having a short product life. The capacitive technique is mainly suited for products having a small or medium size, such as 10 inch or below. The optical technique is one major technique of next-generation sensing techniques, which is not limited to panel size and has a relative stable product life.
Therefore, how to achieve the light touch sensing inside panels becomes to a development direction of the touch technology.